This invention relates to a method for controlling fouling in high efficiency cooling tower fill, particularly in evaporative film media such as Munters fill, comprising adding to cooling water prone to cause fouling which contacts said fill an effective amount of a low molecular weight, water-soluble 2-acrylamido-2-methylpropyl sulfonic acid/acrylic acid-type polymer.
Such polymers are commercially available from Calgon Corporation, Pittsburgh, Pa., as TRC-233.RTM. and TRC-271.RTM..
The use of such polymers is well known in the water treatment art. For example:
U.S. Pat. No. 3,928,196 discloses the use of copolymers of 2-acrylamido-2-methylpropyl sulfonic acid and acrylic acid as scale inhibitors.
U.S. Pat. No. 4,640,793 discloses the use of admixtures containing carboxylic acid/sulfonic acid polymers and phosphonates as scale and corrosion inhibitors.
U.S. Pat. No. 4,618,448 discloses the use of polymers comprising an unsaturated carboxylic acid, an unsaturated sulfonic acid and an unsaturated polyalkylene oxide as scale inhibitors.
Japanese No. 57-084794 discloses the use of copolymers of acrylic acid and allyl polyethylene glycol as scale inhibitors.
European patent application 84301450.7 discloses carboxylic acid/sulfonic acid copolymers in combination with organic phosphonates as scale inhibitors.
U.S. Pat. No. 4,510,059 discloses the use of carboxylic functional polyampholytes to reduce silica deposits in aqueous systems.
U.S. Pat. No. 4,936,987 discloses acrylic acid/2-acrylamido-2-methyl propyl sulfonic acid-type polymer compositions and the use thereof as scale and corrosion inhibitors in water treatment.
U.S. Pat. No. 3,709,816 discloses the use of 2-acrylamido methylpropyl sulfonic acid polymers to fluidize and disperse alluvial deposits in aqueous systems, including cooling towers. This reference does not, however, disclose the efficacy of the instant low molecular weight polymers to control fouling, including biofouling, in high performance evaporative film fills.
U.S. Pat. No. 3,709,815 discloses the use of 2-acrylamido-2-methylpropyl sulfonic acid polymers as boiler water dispersives and conditioners.
While various uses of the instant polymers are widely known in the art, the instant inventors do not believe that the use of low molecular weight, water soluble acrylic acid/acrylamido-2-methylpropyl sulfonic acid-type polymers to control fouling, including biofouling, in high performance cooling tower fill is known or suggested in the art.
In high efficiency hyperbolic natural draft towers, fouling is particularly troublesome. As used herein, the term "fouling" refers to the buildup on or in cooling tower fill media of one or more biofouling agents, alone or in combination with insoluble materials selected from the group consisting of alluvial solids, clays, muds, silts, insoluble metallic scales and metallic salts or oxides. Biological growth, including but not limited to that caused by algae and bacteria, comprises biofouling solids. Such fouling/biofouling adversely impacts the performance of the fill used in cooling towers by plugging the fill, impeding flow through the fill and/or disrupting film formation, thereby diminishing heat transfer.
Evaporative film-forming fills are commonly used in today's cooling towers. These fills comprise flat or formed sheets which are generally made of a plastic material such as polypropylene or PVC. Water films form on these plastic sheets, which facilitates heat transfer between the water film and air passing through the cooling tower. As used herein, "high efficiency cooling tower fill" refers to evaporative film media used in high efficiency cooling towers. This type of fill (for example, Munter's fill) is especially susceptible to fouling in general and biofouling in particular.